1. Field of the Disclosure
This disclosure relates to a sandwich element with a core of mineral wool, and a surface sheet layer, e.g. of metal on each side. The sandwich element comprises adjacently disposed lamellae, where the fiber direction is substantially in a direction perpendicular to the surface of the sheet layer, also denoted the major surface. Sandwich elements of the present disclosure are mounted in connection with each other along one or more side surfaces of the sandwich elements and the side surfaces are cut to facilitate such mounting, e.g. by cutting groove-and-tongue structures in the side surfaces of the elements.
Sandwich elements of mineral wool with a preferred fiber orientation perpendicular to the major surfaces of the element may be used as insulating elements and as fire proof elements. The preferred fiber orientation implies an improved load bearing capacity and the elements may therefore also be used for exterior insulation of roofs and/or building fronts and insulation of floors, and supporting walls because the elements possess a sufficient stiffness or strength and/or insulating property.
These elements are used for the construction of houses, larger buildings such as industrial facilities, production facilities, sport facilities, wholesale/retail outlets, exhibition halls, offices, worker facilities, service outlets, hangars, garages, workshops, administrative buildings, public utility buildings, off-shore constructions, cooling room constructions, storage compartments, and containers.
2. Review of Prior Art
EP0699256 discloses a sandwich element comprising a mineral wool core with sheets attached to each of the major sides of the core. The side surfaces of the elements form a tongue-and groove structure formed from the sheets. The mineral wool core is left uncovered at least over a part of the side surfaces to assure a proper thermal insulation across the joint at the side surfaces between two mounted elements. When the elements are mounted using the tongue-and-groove, the uncovered edges of the mineral wool core remain resting against each other.
This contact between wool in the joint is important for the sake of thermal insulation, and to counteract fire spreading. The mineral wool core of the element is fire-resistant, but crevices may appear in the joint structure that deteriorates the fire resistance performance. Strict manufacturing tolerances are required to enable the core sections of the elements to be jointed tightly with each other. The mineral wool core is made compressible at the joint area. According to a specific embodiment of this concept, the mating area in the joint is provided with a separate sealer strip of more resilient (softer) mineral wool than that used in the element core. According to another embodiment, the joint edge of the element core is severed to include cuts extending toward the interior of the element core and running parallel with the side surface of the element. The purpose of such cuts is again to reduce the compressive strength and to give the element core a greater compressive resilience at its joint side surface.
It is in general known to be a problem to manufacture cuts in the side surfaces such as groove-and-tongue structures in mineral wool which can fullfil the required tolerances, because the cutting tools are subjected to wear in the metallic parts. The result of using such cutting machinery which has been subjected to wear by cutting in the abrasive mineral wool is that the tongue-and-grooves part structures of the side surfaces of the element become ill-defined and crevices and variations in the side surface results. This again, leads to a build-up of thermal bridges because there is no direct wool-wool contact across the tongue-and-groove joint when two adjacent sandwich elements are connected to each other. The cutting machinery therefore requires frequent maintenance to provide the strict tolerances of the cut surface in the mineral wool.